This invention relates to a delivery system to process a hot workpiece discharged from a rolling mill or the like by subdividing the workpiece into lengths while directing the lengths in succession to a run-out transfer for cooling. More particularly, the present invention relates to such a delivery system to subdivide a rolled workpiece into finished lengths while traveling at a high speed and to direct the successive sheared lengths of workpieces to individual retardation channels for deceleration and transfer in a direction lateral to the extended length of the sheared workpiece.
While not so limited, the present invention is particularly useful in a rolling mill installation where it is desired, at the delivery side of the last mill stand, to handle the workpeice without coiling by subdividing the workpiece, e.g., a rod or a bar, into desired finished lengths while traveling at a relatively high delivery speed of up to 4000 feet per minute or greater. The production of single finished lengths of bar at very high speeds has not been practical before this invention due to shearing, separating and guiding problems. Due to the use of a continuously-running flying shear in combination with synchronized inlet and outlet guiding equipment and a suitable arrangement of all the components, the equipment according to this invention can handle the high speeds and the rapidly repeating cuts required to cut finished salable lengths of bar. Thus, for example, 200 cuts per minute are necessary to produce finished cut lengths of 20 feet when a workpiece is traveling at a speed of 4000 feet per minute. The successive lengths of sheared hot workpieces are cooled and transferred to a cradle for strapping and shipping, thus eliminating the need for recutting and further handling.
It was common practice in the past to deliver the bar product from the last stand of a merchant bar mill to a hot bed where the product was transferred laterally to its extended length across the bed and then fed to a shear for subdivision into desired finished lengths. Even the production of multiples of finished lengths of bar above 1800 feet per minute has been difficult because at this speed, the commonly-used start and stop shears in combination with hot metal detectors and accompanying guiding equipment become unreliable. Bar products of varying cross-sectional shapes can be produced on a cross-country mill at about 800 feet per minute. Other mill arrangements permit the production of such bar products at greater speeds. One such mill arrangement is shown in my prior U.S. Pat. No. 3,945,234. The tandem rolling mill arrangement disclosed in this patent is readily capable of producing bar or rod products down to at least 3/8 inch in diameter at speeds in excess of 4000 feet per minute. The versatility of the tandem rolling mill arrangement permits its addition to an existing cross-country mill whereby the delivery speed from the mill can be increased to several times the delivery speed of the cross-country mill. A rolling mill installation of this type is particularly suitable for producing small round sections and rebar, although it can be adapted for small shapes.
A handling system for the hot bar issuing from the last stand of the rolling mill must accommodate the high speed of operation without jamming up. The bar product must be severed precisely into desired lengths and the required cooling equipment must be suitable to handle the multitude of workpieces coming from the shear. Moreover, subdividing the workpiece issuing from the mill stand into finished lengths greatly increases the product yield when the mill is coupled to a continuous casting line or other well-known process for supplying long lengths of workpieces to the mill.
A critical requirement of a high-speed delivery system for a rolling mill of the above type is the necessity to separate the tail end of one sheared length from the front end of the following and remaining length of workpiece as an incident to the shearing operation. As the leading length of the sheared workpiece decelerates, it is necessary that the workpiece which immediately follows can slide past the tail end of the decelerating workpiece without interference. Unless this necessary and controlled separation of sheared lengths of workpieces can be achieved, successive workpieces would move into each other during deceleration.